VICINITY: A Pinch of Randomness Brings out the Structure

Abstract. Overlay networks are central to the operation of large-scale decentral-ized applications, be it Internet-scale P2P systems deployed in the wild or cloud applications running in a controlled—albeit large-scale—environment. A num-ber of custom solutions exist for individual applications, each employing a tailor-made mechanism to build and maintain its specific structure. This paper addresses the role of randomness in developing and maintaining such structures. Taking VICINITY, a generic overlay management framework based on self-organization, we explore tradeoffs between deterministic and probabilistic decision-making for structuring overlays. We come to the conclusion that a pinch of randomness may even be needed in overlay construction, but also that much randomness or ran-domness alone is not good either.